Electromagnetic driver



Oct. 18,1927; 1,645,583 C. A. BRIGHAM ET AL- ELECTROMAGNETI C DRI VER Filed Aug. 22, 1925 l Ei l li FIG. 3

CYF/L A BRIGHAM WILLIAM H GEE/vs INVENTOR5 BY M [7 AITORNEY- Patented Oct. 18, 1927.

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GYRIL A. BRIGI-IAM AND WILLIAM H. GERNS, OF EAST ORANGE, NEW JERSEY, AS- SIGNORS TO BRANDES LABORATORIES, INC., OF NEWARK, NEW JERSEY, A COR- PORATION on NEW JERSEY.

ELECTROMAGNETIC DRIVER.

Application filed August 22, 1925. Serial No. 51,819.

Our invention relates broadly to electromagnetic sound reproducers and more particularly to a construction of electromagnetic driver for the stylus needle of phonographs.

One of the objects of our invention 1s to provide a phonograph attachment by which electrical vibrations may be employed to actuate the stylus of a phonograph sound box for reproducing radio concerts and other entertainment through the sound amplifying horn of a phonograph.

Still another object of our invention is to provide a driving force for convertmg electrical vibrations into sound, where an electromagnetic system may be adjusted with respect to .an armature member and the armature member so positioned withrespect to the pole pieces of the electromagnetic system .as to impart a maximum driving force to the sound reproducing system.

We have illustrated the driving force of our invention as particularly adapted as an attachment for phonographs, but we desire that it be understood that the vibrations delivered by the armature member may be utilized for actuating a cone diaphragm or other sound reproducing system.

Our invention will be more clearly understood from the specification hereinafter following by reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view showing the operating parts of the driving force and the position'ofthe stylus needle of a phonograph with-respect to the vibratory member of the driving force; Fig. 2 is a plan view of the armature member which is carried within the casing of the electromagnetic driver; and Fig. 3 is a side view of the armature member and the actuator from which sound vibrations are delivered.

with reference to the drawings in more detail reference character 1 designates a screw threaded base member which carries the electromagnetic system of the driving force. The electromagnetic system comprises angle pieces 2 and 3, which are preferably laminations which form the pole pieces for the electromagnets and are bound together by means of rivet members 4. Electromagnets 5 and 6 are disposed on the pole pieces 2 and 3 and connected through terminal posts 7 and 8 with the exterior operating circuit. A permanent magnet 9 is secured in position with respect to the angle pieces 2 and 3 by means of screws 10 and 11. The screw threaded base member 1 engages internal screw threads within casing 12. The casing 12 is closed by an end plate 14; having an inwardly extending annular tongue 15 which serves as a seat for opposite ends of armature member 16. The armature member 16 is gripped at its opposite ends by means of an annular tongue 17 extending from the adjustable ring member 18. A resilient operating gasket 19 is positioned between the adjustable ring member 18 and the screw threaded base member 1 for locking the electromagnetic operating mechanism in a fixed position when it is revolved by means or control knob 20, which engages an outwardly extending portion 21 on the screw threaded base member 1. The armature 16 comprises a magnetic sheet of material of suit-- able flexibility and rigidity which is substantially rectangular in shape, but is enlarged at its center portion 22. A rod member 28 is riveted at 24 to themidpoint of the portion 22 of the armature 16 and protrudes outwardly through the end plate 14 through the aperture 25 in the end plate 1 1. A head 26 is formed on the extremity of the rod member 23 and has a depression 27 therein which serves as a seat for stylus needle 28 of a phonograph sound box 29. The rod member 22 in the process of wiggling in a horizontal direction imparts vibratory move ment to the stylus needle 28 which in turn actuates the sound box 29 for converting the mechanical vibrations into sound. The sound is delivered through the tone arm of the phonograph to the sound amplifying horn of the phonograph.

The housing for the electromagnetic driver may be enclosed in a suitable casing, so that it may be readily mounted adjacent the rec 0rd table of a phonograph and the stylus needle of the phonograph readily dropped into the seat of the protruding member 23 so that radio broadcast signals received through the usual radio receiving apparatus may be utilized to drive the sound box repro ducer. As we have previously noted our driver may also be used for actuating a cone phragm.

The sound vibrations may be taken from said armature member from a point away from the center thereof in such manner that the driving force which is applied to the armature me-mb may en'ipley a lever principle, where the load may be taken off at some point between the applied power and the fulcrum.

We have described one 01'' the preferred embodiments of our invention, but we desire that it be understood that modifications may be made and that no limitations upon the invention are intended other than are imposed by the scope of the appended claims.

What we claim and desired to secure by Letters Patent oi the United States is as follows:

1. An electromagnetic driver comprising in combination an annular "asing havin one end thereof substantially closed, internal screw threads at the other end of said casing, a rotatable screw tl'ireaded plate member in said casing an electromagnetic operating mechanism carried by said rotatable screw threaded plate member, an' arn'iaturc member positioned in the opposite end of said casing, said armature member comprising a substantially rectangular strip of magnetic material with an enla ged portion of said strip located substantially at the center thereof adjacent said electronuignetic operating mechanism, and a rod member protruding from the enlarged portion 0t said armature and shaped at its outer extremity to receive a stylus therein.

2. An electromagnetic driver and sound reproducer comprising in combination an annular casing having one end thereof substantially closed by a wall integral with the casing, with the other end thereof internally screw threaded, an annular supporting face extending inwardly in said casing trom said anism carried by said screw threaded plate,

whereby said electromagnetic ope 'ating mechanism may be adjusted with respect to said armature member and a rod member protruding from said armature member.

3. An electromagnetic sound reproducer comprising in combination an electromag netic driver having a casing, an electromagnetic operating mechanism in one end of said casing, a substantially rectangular strip constituting an armature positioned in the 0pposite end 01 said casing, a horizontally protruding rod member connected with said armature, said rod member having a head at its outer extremity with a seat therein arranged to receive a stylus needle.

4. In an electromagnetic sound reproducer the combination of a casing, an electromagnetic operating mechanism carried in one end of said casing, an armature member carried in the opposite end of said casing and ar ranged to be actuated by said electromagneti'c operating mechanism, a rod member connected to said armature member and extending substantially at right angles with respect thereto said rod member having a head at its outer extremity with a depression in said head arranged to receive a stylus needle therein.

In testimony whereof we aifiX our signatures.

C YRILA. BRIGHAl/I. WILLIAM H. GERNS. 

